The Yaf_Action_Abstract class

(Yaf >=1.0.0)

Introduction

A action can be defined in a separate file in Yaf(see
Yaf_Controller_Abstract). that is a action method
can also be a Yaf_Action_Abstract class.

Since there should be a entry point which can be called by Yaf (as of PHP 5.3,
there is a new magic method __invoke, but Yaf is not only works with PHP 5.3+,
Yaf choose another magic method execute), you must implement the abstract method
Yaf_Action_Abstract::execute() in your custom
action class.